1. Field of the Invention
The present invention relates to a braking system.
2. Discussion of the Background
Some of hydraulic braking devices widely used in vehicles such as motorcycles are configured in such a manner that a brake input side where an operator causes a fluid pressure to be generated in brake fluid by operating a brake operating unit and a brake output side where the fluid pressure acts on wheel braking means are allowed to be brought into communication or out of communication by an electromagnetic opening and closing valve.
As an example, a braking device of so called a “bi-wire” braking device which electrically detects an amount of operation of the brake operating unit, controls a power unit on the basis of a detected value to generate a fluid pressure, and activates the wheel braking means is known. For example, see JP-A-2008-6850.
According to FIG. 1 in JP-A-2008-6850, a fluid pressure circuit 1 as a brake circuit on a front wheel side includes a master cylinder 3 configured to generate the fluid pressure by an operation of a brake operating unit 2 as a brake lever, a brake caliper 4 provided on the front wheel, a fluid pressure modulator 6 configured to generate a fluid pressure by a motor, and a reaction force simulator 9 configured to cause the brake operating unit 2 to generate a pseudo reaction force according to the operation of the brake operating unit 2.
The master cylinder 3 and the brake caliper 4 are brought into communication by a main brake channel 5, and a first electromagnetic opening and closing valve V1 is provided in the main brake channel 5, the master cylinder 3 and the reaction force simulator 9 are brought into communication by a branch channel 8, a second electromagnetic opening and closing valve V2 is provided in the branch channel 8, the fluid pressure modulator 6 and the brake caliper 4 are brought into communication by a supply and exhaust channel 7, and a third electromagnetic opening and closing valve V3 is provided in the supply and exhaust channel 7.
When electricity is not distributed, the first electromagnetic opening and closing valve V1 is opened, and the second electromagnetic opening and closing valve V2 and the third electromagnetic opening and closing valve V3 are closed.
For example, when a bleeding operation to release air in the fluid pressure circuit 1 is performed, as regards the main brake channel 5 from the master cylinder 3 to the brake caliper 4, bleeding from a bleeding hole provided on the brake caliper is possible by causing the master cylinder 3 to generate the fluid pressure by operating the brake operating unit 2 since the first electromagnetic opening and closing valve V1 is opened, but the bleeding cannot be achieved because the second electromagnetic opening and closing valve V2 and the third electromagnetic opening and closing valve V3 provided in the branch channel 8 from the master cylinder 3 to the reaction force simulator 9 or the supply and exhaust channel 7 from the fluid pressure modulator 6 to the brake caliper 4 respectively, are closed.
Therefore, in order to perform the bleeding, a computer which issues an instruction to an ECU which controls the second electromagnetic opening and closing valve V2 and the third electromagnetic opening and closing valve V3 from the outside is needed to distribute electricity to the second electromagnetic opening and closing valve V2 and the third electromagnetic opening and closing valve V3. An operation to connect the computer as such is complicated, and hence a simpler operation is desired.